The purpose of the proposed research is to demonstrate the direct application of research based theory of coping to the clinical practice of nursing. An informational intervention based on traditional teaching- learning guidelines will be contrasted with an informational intervention guided by research and theory on coping. The hypothesis is that radiation therapy (RT) patients who receive an informational intervention based on research and self-regulation theory of coping and following RT, as compared to patients who receive only information included in traditional patient teaching. A variable that may mediate the effects of the experimental intervention will be explored. Individual differences variables of generalized optimistic-pessimistic expectations about outcomes and preference for information will be included to determine if some patients benefit more than others from the experimental intervention. The study design is quasi-experimental with intact groups of patients who will receive either the traditional nursing care currently being delivered or experimental nursing care. A training program for staff nurses will be instituted before the experimental nursing care is delivered. Procedures are included to protect internal validity of the study, including monitoring of the nursing care delivered. The sample will consist of patients with head and neck, lung, or breast cancer who are receiving RT for cure or control of cancer. Emotional response, measured with a brief form of the Profile of Mood States, and disruption in usual activities, measured with selected subscales of the Sickness Impact Profile, are the outcome variables that will be measured both during RT and one and three months posttreatment. Baseline measures of individual difference, outcome and mediating variables will be taken. Analysis of variance using baseline, clinical, and demographic variables as covariates will be used to test hypotheses about the effects of the intervention and individual differences on outcomes. Regression analyses will be used to evaluate mediating effects.